Application of switchable solvent-based liquid phase microextraction for preconcentration and trace detection of cadmium ions in baby food samples

In this paper, switchable solvent-based liquid phase microextraction was developed for preconcentration of cadmium ions and its detection by flame atomic absorption spectrometry. 2,9-dimethyl-1,10-phenanthroline (neocuproine) was used as a complexing agent in the developed sample preparation method. Conversion features of triethylamine and protonated triethylamine bicarbonate were used as a switchable solvent pair. Protonated triethylamine bicarbonate as polar form of switchable polarity solvent was successfully synthesized from triethylamine via proton transfer reaction and used for microextraction of hydrophobic cadmium complex with 2,9-dimethyl-1,10-phenanthroline at pH 7.0. The factors influencing the extraction procedure were investigated and optimized. Under the optimized conditions, limit of detection, limit of quantification, and enrichment factor for the proposed method were 0.02, 0.1 mu g L-1, and 54.2, respectively. The calibration curve was linear in the range of 0.1-60 mu g L-1 with a correlation of determination (r(2)) of 0.99. The relative standard deviation for determination of 40 mu g L-1 of Cd (II) was 3.1% (n = 6). The intraday and inter-day precisions for real samples analysis were in the range of 4.4-5.6 and 4.9-5.7%, respectively. The proposed method was applied for the determination of cadmium in baby food samples with satisfactory analytical results. In comparison with other methods, the proposed method is very easy, rapid, simple, and sensitive for determination of cadmium at trace levels in complex matrices.